The outage knocked power out in a 24-mile-wide (40-kilometer) stretch from Havana’s western residential neighborhoods across the city’s center and Old Havana district and on to suburbs on the other side of the bay.

In Havana’s Vedado entertainment and business district, the only buildings with visible light were tourist hotels and upscale apartment towers, which have backup generators.

Big blackouts were common in Havana a decade ago, when Cuba had an energy crisis. Isolated outages still hit the city on occasion, but citywide blackouts have become rare.